Changes nsIPermissionManager.idl to accept type strings rather than integers; this allows consumers to register unique types more easily, without fear of conflicting with an already-existing one. Also fixes some bounds-checking fu (sr=bz on irc for those additional portions). patch by mvl; r=dwitte, sr=bz. git-svn-id: svn://10.0.0.236/trunk@144606 18797224-902f-48f8-a5cc-f745e15eee43